Method of and apparatus for applying metal sheathing to insulated conductors



. 2, H94@ J, D BURBY 2,185,429

METHOD 0F AND APPARATUS Foa APPLYING METAL SHEATHING To INSULATED coNDUcToRs Filed May 8, 1957 :s sheets-sheet 1 INVENT'OR JQMES Blf/P5K ATTORNEYS J. D. BURBY Jam, 2, E94@ METHOD 0F AND APPARATUS FOR APPLYING METAL SHEATHING TO INSULATED CONDUCTORS 3 SheecS-SheerI 2 Filed May 8, 1937 4 R m im! ilnl AIMEJDBf/Px AT1-o R N Ys Jan. 2, 14W J. D. BURBY 2,185,429 I METHOD 0F AND APPARATUS FOR APPLYING METAL SHEIATHING T0 INSULATED CONDUCTORS 3 Sheets-Sheet 5 Filed May 8, 1937 Q kk ATTORNEYS Patented Jan. 2, 1940 A UNITED STATES PATENT GFFICE METHD OF AND APPARATUS FOR APPLY- ING BIETAL SHEATHNG TO INSULATED CONDUCTORS Application May 8, 1937, Serial No. 41,424

21 claims.

cooled, for example, by passing Water or other cooling medium therethrough. The sheathing l@ metal in a molten state is fed to an elongated mold surrounding the cooling sleeve and as the sheathing metal cools, it is advanced and later subjected to an operation, which reduces the diameter thereof and brings the sheath into a fairly 'III snug fit with -the insulated conductor. .The forward feed of the plastic or partially solidified sheath metal, in some cases, will be assisted by rotating the mold and providing it with rifling or thread-like projections on the interior sur-- face thereon. This forward feed Will also be as 2@ sheathing metal will serve to assist in the forward feed thereof.

For a further more detailed disclosure of the invention, reference is to be had to the following specification, the appended claims and the accom- 3@ panying drawings.

In the drawings- Fig. 1 is a view partly in elevation and partly in section illustrating novel apparatus for carrying out the improved method; Fig. 2 is an en larged vertical longitudinal section through that Aportion of the apparatus in which the sheathing metal is solidified and reduced in diameter; Fig. 3 is an enlarged detail of parts shown in Fig. 2; Figs. 4 and 5 are detached details of parts shown in Fig. 2; Fig. 6 is a section of a swaging head for reducing the diameter of the solidified or partly solidified sheath, the view being taken approximatelyon line 6-6 of Fig. 2; Fig. 7 is a view similar to Fig. l illustrating an alternative embodiment of the invention, wherein the pressure of inert gas is imposed on the body of molten sheathing metal to facilitate the longitudinal feed thereof; Fig. 8 is a detail view illustrating the provision of means for electfically"maintaining 50 the sheathing metal in a molten or plastic state.

- cablevC covered with suitable insulation previously wrapped on or otherwise applied is fed over a 55 guide sheave Ill and downwardly through a coolving device indicated as a whole at I2, through which water or other cooling medium is circulated, the cooling medium being supplied by pipe It and carried away by an outlet pipe IG, these pipes being connected with a header I8 having a division wall 20 therein.V The header carries a plug 22, to which is secured an elongated piece of guide tubing 2li. Surrounding the tubing 2t, there is another tube 26. The internal diameter of the tubing 24 isgof -a size to permit the insulated cable or conductor C to pass freely therethrough and the arrangement of the nested tubes 2li and 26 within the sleeve l2 is such that the cooling medium entering by way of pipe I4 flows downwardly through the space between these two tubes and then upwardly through the annular space between the tube 26 and the outer shell I2 and thence to a suitable discharge point or vessel by way of pipe I6. In this way, a constant body of Water or other cooling medium is circulated in heat exchange relationship with the longitudinally advancing insulated conductor or cable so that, as the molten metal sheath is formed thereon in the manner to be presently described, the heat of the molten metal will not have a deleterious effect on the insulation of the conductor or cable.

Y Molten sheathing material, such as lead or the like is fed from a melting pot 28 into a vessel 30 to the bottom of which is connected an outlet pipe 32, which terminates in a dome-like member 34, which communicates with the interior of an elongated mold 36, to which is keyed a gear 38 by means of which it is rotated by the pinion 40 and shaft 42, the latter being driven through a bevel gearing MI and 46, from a drive shaft 48 connected'with any suitable source of power, such as an electric motor or the like, not shown. The interior of the rotary mold 36 is provided with helical riiiing projections 50 and the exterior of the sleeve I2 is provided with one or more longitudinally extending ribs 52. As the mold 36 is rotated, the helical projections 50 exert a screwlike action thereon, which in cooperation with the longitudinal ribs 52 formed on the sleeve I2 acting on the solidified or plastic part of the sheathing metal, tends to feed the sheath metal longitudinally downward. It Will be noted that, as the conductor C is being fed longitudinally, the molten sheathing metal is being simultaneously fed therearound and that the rotary mold imparts somewhat of a whirling motionto the sheathing metal, but only in the non-solidied portion'thereof in the upper part of the mold 36. In the lower part of the mold, where the metal has'solidiiied, it acts as anut which does not rotate but which is advanced longitudinally by the rifling projections 50 and ribs 52. The forward feed of the sheath metal is assisted by the weight of the metal, the screw-thread like action of the helical projection 50 in cooperation with the longitudinal ribs, thus a sheath of a diameter` greater .than that of the conductor forms around the latter as it is advanced longitudinally.

A further feature of the present invention relates to the concurrent reduction of diameter in this relatively larger sheath immediately after the metal thereof becomes plastic or solidified. This is accomplished by subjecting the relatively larger diameter portion of the sheath to a swaging operation, whereby the relatively larger diameter sheath is made to make a fairly snug or neat lit with the insulated conductor. To 'accomplish this, I provide suitable means for working the metal immediately .after it has solidied.

In the embodiment of the invention illustrated,

means for working the metal is in the form of carried in a cage member 60, the outer portions of these rollers riding on a hardened race ring Y 62. The hammers 5B areslidable radially in a groove 64 of a member 66 having an elongated hub 68, to which is keyeda gear 'I0 and a fly- Wheel 12. 'I'he lower end of the hub 68 is mounted in a suitable roller bearing 14 secured in a hub portion 16 of a bracket 18 carried by the frame 19. The gear 'l0 meshes with the gear 80, which is driven through other transmission gears 82, 84 and 86 from the gear 88 keyed to the shaft 42. T he ratio of this gearing will be such as to properly coordinate the speed of the swaging action with the longitudinal feed applied to the sheath by the gearing 38-40, which rotates the'mold portion 36.

Extending into the plane of the swaging die members 54 and secured to the lower extremity of the sleeve I2, ,there is a tapered cap 90, which serves to close the end of the sleeves I2 through which the cooling medium is circulated and which also serves as a' lower support for the lower extremity of the innermost tube 24. This cap is tapered so as to properly coact with the converging faces 9| of the reciprocating dies 54 and thus it cooperates with the swaging members in bringing about' the gradual reduction of the sheath metal from the large diameter at which it is originally formed to the smaller diameter, to which it is transformed as a result of the swaging operation.

The swaging operation performs a cold or plastic working of the wall of the centrifugally cast sheath metal immediately after it solidies or has been permitted to become plastic and has the effect of making the resulting sheath more homogeneous than would be the case with a sheath extruded from a thick static annular mass to the nally desired diameter as is the case when the conventional lead press is used.

By my cold working of centrifugally cast metal and simultaneous reductionin diameter of the sheath,`I thus improve the characteristics ofthe resulting cable sheath. My novel method also has the advantage' that a much smaller expenditure of power is required to form the sheath t o thedesired small diameter,` than would be the sheath downward.

method also has the added advantage of making it possible to form a sheath of indefinite length .without the inclusion of objectionable joints,

seams, laps, welds, or other defects common to the extrusion process.

In some cases, instead of eecting the longitudinal feed of the solidied sheath metal' by the use of riling or screw thread-like projections, as in Figs.l 2 and 4, I may provide means for applying a feeding pressure of inert gas to the top of the molten body of metal. Such modification is illustrated in Fig. 7. In this figure, a gas supply tank 90 is connected lby pipe 92 having a valve 94 therein for supplying gas to a chamber 96 'surrounding a member 98 corresponding to the shell I2, shown in Fig. 2. In this modification, the molten metal is supplied i'rom a vessel 30 which is connected by a pipe 32' with a tting 34', as clearly shown. The vessel 30 may be heated by a gas Aburner indicated diagrammatically at |00. A pressure of inert gas may be imposed on the body of metal in the vessel 30', there being a pipe |02 connecting the vessel with the gas supply tank 90, this pipe having a control valve |04 therein.

Normally, the valves 94 and |04 will be open,

thus the pressure of gas from the tank 90 will be exerted at substantially the same unit pressure on the top of the bodies of metal in the chamber 96 and in the vessel 30. 'I'his pressure will tend to assist the longitudinal feed of the sheath being formed by cooperation of the mold 36, which may then be stationary or rotating. When the supply of metal in the vessel 30' becomes depleted, it is merely necessary to shut the valve |04 to permit filling of the vessel without interrupting the operation of the machine, it being apparent that the amount of molten metal in the chamber 96 Will be sufilcient to permit the machine to operate for a short interval of time while the supply of metal to the vessel 30 is being replenished.

In either of the arrangements of apparatus illustrated in Fig. 2 or '7, heating means may be applied for maintaining the sheath forming metal at the temperature required to maintain the metal in a molten state.

Suitable means for maintaining the metal molten is illustrated in Fig. 8, wherein I have shown an electric heater comprising a heating element |06 carried by a suitable insulator sleeve |08, which is surrounded by an outer casing ||0. The mounting for the heater element may be stationary and the mold 36' may be rotated by a gear ,38' corresponding to the gear 38 of Fig. 2.` In this modlilcation of Fig. 8, the upper portion of the metal holding vessel |I2 is provided with an open-topped funnel portion H2, into which the metal may be periodically introduced. The shell I2, gearing for driving the mold and swaginghead and other related parts may be' regarded as substantially the same as the construction shown in Fig. 2. The molten metal in Fig. 8 will provide a suicient head or pressure to assist in feeding the solidified While I have described quiteprecisely certain specific method steps and a particular combination of instrumentalities used in the method it is not to be construed that I am strictly limited thereto since various changes both in the method steps and in the instrumentalities utilized may bemade by those skilled in the a'rt without departure from the invention .as deflned in the appended claims.

lating a confined cooling mediumr in heat ex-4 change relationship therewith in the zone intermediate the conductor and the surrounding molten metal, allowing part of the metal to solidify and thus form a tube-like body of greater diameterA than the insulated conductor to be covered,t feeding said body longitudinallyand subjecting it-to forces which materially reduce 'its diameter.

2. In the manufacture of metal sheathed conductors, the method of which comprises longitudinally advancing the conductor to be sheathed, during said advance flowing an annular body of molten metal therearound but spaced radiallyv therefrom, circulating a connedcooling medium in an annular longitudinal zone between the insulated conductor to be covered and the annular molten body of metal, allowing the lower portion of the metal to solidify around the insulated conductor and thereupon subjecting the solidified metal to repeated blows so as to reduce the external diameter thereof substantially or approximately to a size to suit that of the insulated conductor.

3. In the manufacture of metal sheathed insulated conductors, the method which comprises advancing an insulated conductor longitudinally downward while disposed in substantially upright position, flowing an annular body of molten metal to a zone spaced radially from the insulated conductor, causing the lower portion of the annular body of metal to solidify while it is moving downwardly and subjecting the solidified metal to an operation effective to reduce the internal diameter thereof to approximately that of the external diameter of the insulated conductor.

4. In the manufacture of nietal sheathed insulated conductors, the method which comprises advancing an insulated conductor longitudinally downward while disposed in substantially upright position, fiowing an annular body of molten metal to a zone spaced radially from the insulated conductor, causing the lower portion of the annular body of metal to solidify while it is moving downwardly and subjecting the solidified metal to a rapid succession of blows at peripherally spaced points so asl to reduce the internal diameter-- of the annular metal body to a size to suit that of the external diameter of the insulated conductor.

5. In the manufacture of metal sheathed electric conductors, the method which comprises disposing the body of molten metal around a longitudinally moving insulated conductor, imposing a fluid pressure on said body of molten metal to effect a movement thereof in the direction of feed of the conductor, allowing a portion of the metal to solidify, subjecting the solidified portion to a rapid succession of blows so as to reduce the diameter of the metal body to a size to suit that of the insulated conductor which it encloses.

6. In an apparatus for the manufacture of metal sheathed electric conductors, means for disposing agbody of molten metal around a longitudinally moving insulated conductor, means for circulating a confined cooling medium in the zone intermediate the conductor and the surpressure of gas on one portion of the molten metal while allowing a portion remote therefrom to solidify, and rapidly moving means for subjecting the solidied portion of the' metal to forces to reduce its diameter to suit that of the insulated conductor.

7. Apparatus of the character described comprising a rotatably mounted mold carrying a body of molten metal, a shell extending longitudinally therethrough, a conductor guide within the shell, means for circulating a cooling medium through the shell and in contact with said guide, means for longitudinally feeding vthe annular body of lmetal solidied in the mold and rapidly comprising a rotating mold'carrying a body o f molten metal, a conductor guide extending longitudinally through the mold, cooling means within the mold surrounding the conductor guide, means responsive to the rotation of the mold for longitudinally feeding the annular body of metal solidified therein about the c onductor guide andmeans effective to reduce the diameter of solidified metal fed from the mold.

9. An apparatus of the character described comprising a rotating mold carrying a body of molten metal, a conductor guide extending longitudinally through the mold, cooling means within the mold surrounding the conductor guide, means responsive jto the rotation of the mold for longitudinally feeding the annular body of metal solidified therein about the conductor guide and rotary swaging means adjacent the exit end of the mold effective to materially reduce the diameter of the tubular body of solidified metal fed therefrom.

10. Apparatus of the character described comprising a rotating mold, guide means for an insulated cable extending Y longitudinally therethrough, means for accommodating a cooling medium circulating in heat exchange relationship with the guide means, means whereby rotation of the mold imparts a longitudinal feed to the tubular body of metal solidified therein, and means disposed adjacent the exit end of the mold for reducing the diameter of the tubular body fed therefrom.

l1. Apparatus of the character described comprising an elongated mold, a shell extending therethrough, a guide for an insulated conductor extending through the shell, means for circulating the cooling medium through the shell, so as to protect the insulation on the conductor fed through the guide, means for supplying molten metal to the mold, means vfor rotating the mold ,and respective means on the interior of the mold and on the exterior of said shell eiective upon rotationl of the mold to longitudinally advance the metal solidified therein.

12. Apparatus of the character described comprising an elongated mold, a shell extending therethrough, a sleeve disposed within the shell serving as a guide for an insulated conductor, means for circulating a cooling medium through the shell so as to protect the insulation on the conductor fed through said sleeve, means for supplying molten metal to the mold, means for feeding the metal solidified in the mold longitudinally thereof and mechanically actuated swaginggmeans adjacent the exit end of the mold effective to reduce the diameter of the` annular body of metal emerging therefrom.

13. Apparatus of the character described comand respective means on the interior of the molcl prising an elongated mold, a shell extending therethrough, a guide for an insulated conductor extending through the shell, means for circulating the cooling medium through the shell, so as to protect the insulation on the conductor fed through the guide, means for supplying molten metal to the mold, means for rotating the mold,

and on the exterior of said shell 1effective upon rotation of the mold to longitudinally advance the metal solidified therein and swaging means disposed adjacent the exit end of the mold effective to reduce the diameter of the annular body of solidied metal emerging from the mold.

14. Apparatus of the character described comprising a vertically disposed rotatably mounted mold carrying a body of molten metal, a shell extending longitudinally therethrough, a conductor guide Within the shell, means for circulating a cooling medium through the shell and in contact with said guide, means for longitudinally feeding the metal solidified in the mold and rotary swaging means eiective to reduce the diameter of solidied metal fed from the mold and common driving mechanism for' said mold and said swa'ging means including gearing whereby the longitudinal advance of the solidified metal elected by the rotation of the mold is properly coordinated with the operation of the swaging means.

15. An apparatus of the character described comprising an elongated mold, a shell extending therethrough, a guide sleeve 'within the shell for a longitudinally advancing insulated conductor, means fon circulating a cooling medium through the shell so as to protect the conductor insulation, means for supplying molten metal to the mold, means for applying gas pressure to the metal Within the mold so as to elect the feed of the solidified portion therethrough and flow applying means adjacent the exit end of the mold elective to reduce the diameter of the metal body emerging therefrom.

16. An apparatus of the character described comprising a vertically' disposed elongated mold, a shell extending therethrough, a sleeve disposed Within the shell serving as a guide for an insulated conductor, adapted to be advanced therethrough, means for circulating a cooling medium through the shell so as to protect the insulation on the conductor fed through the guide, means in communication with the mold for retaining a body of molten metal and a. heating' element surrounding said retaining means so -as to normally maintain the metal therein ln a molten state.

17. The method of forming a continuous metal 4sheath about an electric conductor, which comprises disposing a body of molten metal around a longitudinally moving insulated conductor, so-

' lidifying said'metal to a tube-like body of greater inner diameter than the exterior diameter of the insulated conductor, feeding the tube-like body with the insulated conductor, and mechanically reducing the diameter of said tubelike body about said conductor.

18. The method of forming a continuous metal sheath about an electric conductor, which comprises disposing a body of molten metal around a longitudinally moving insulated conductor, solidifying said metal to a tube-like body of greater inner diameter than the exterior dig ameter of the insulated conductor, and swaging said tube-like body'about said conductor to reduce lts diameter.

19. The method of forming a continuous metal sheath about an electric conductor, which comprises disposing a body of molten metal around a longitudinally moving insulated conductor, internally cooling said metal to solidify it to a tube-like body moving with said conductor, and swaging saidtube-like body to reduce its diameter.

20. The method of forming a continuous metal sheath about an electric conductor, which comprises disposing a body of molten metal around a v longitudinally moving insulated conductor, cool- 

